Electronic combination lock and theft prevention device

ABSTRACT

The electronic theft prevention or detection device operates on the principle that the direction of electron flow can be detected and determined to be &#39;&#39;&#39;&#39;correct&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;incorrect.&#39;&#39;&#39;&#39; An electrical path connected to the parallel combination of a diode and a relay coil is provided in that portion of an ignition circuit which would normally be &#39;&#39;&#39;&#39;hot wired&#39;&#39;&#39;&#39; by a thief. The jumping or &#39;&#39;&#39;&#39;hot wiring&#39;&#39;&#39;&#39; of the ignition circuit operates the relay coil which can actuate an alarm or means for preventing operation of the engine. If so desired, the conventional ignition key and lock arrangement can be replaced by a novel electronic combination lock, which may also be used for a host of other purposes.

United States Patent Inventor Ian H. MacFarlane 15525 Frazho Road,Roseville, Mich. 48066 Appl. No. 10,521

Filed Feb. 11, 1970 Patented Jan. 1 1, 1972 ELECTRONIC COMBINATION LOCKAND THEFT PREVENTION DEVICE Primary Examiner-Herman J. HohauserABSTRACT: The electronic theft prevention or detection device operateson the principle that the direction of electron flow can be detected anddetermined to be correct" or incorrect." An electrical path connected tothe parallel combination of a diode and 'a relay coil is provided inthat portion of an ignition circuit which would normally be hot Wired"by a thief. The jumping or hot wiring of the ignition circuit operatesthe relay coil which can actuate an alarm or means for preventingoperation of the engine. If so desired, the conventional ignition keyand lock arrangement can be replaced by a novel electronic combinationlock, which may also be used for a host of other purposes.

70 AccessoR/ES PATENTEU JAN] 1 I972 3.634.697

sum 1 UF 3 INVENTOR IAN H. MACFARLANE ATTORNEY PATENTEU JAII I I 1972SHEET 2 BF 3 FIGB INVENTOR IAN H. MACFARLANE ATTORNEY SHEET 3 OF 3PATENTEU Jam 1 I972 INVENTOR IAN H. MACFARLANE I ATTORNEY ELECTRONICCOMBINATION LOCK AND TI-IEFI" PREVENTION DEVICE The present inventionrelates to an electronic theft prevention or detection device, and alsorelates to an electronic combination lock which may be used inconjunction with the mentioned theft prevention or detection device orused in other environments or applications. In particular, the inventioncan be utilized to control, detect or prevent the starting of any engineor other apparatus which requires a source of electrical power.

The inventive electronic sequential combination lock can be utilized toprovide sequential operation in a momentary contact push button-operatedlocking control for direct current electrical apparatus, and can beadapted to control alternating current apparatus to regulate, control,detect or prevent the action of various solids, fluids, or othersubstances.

One of the many possible embodiments of the invention relates to theminimizing or completely eliminating the very serious and increasingproblem of theft of motor vehicles. The problem of stolen motor vehicleshas become very widespread throughout the world. For example, during1968, one out of every I08 automobiles registered in the United Stateswas stolen. This resulted in a loss of approximately $270,000,000, whichin turn will be added to motorists insurance premiums. The theft oflate-model automobiles has become such a big business that many of the300 car gangs identified by the Federal Bureau of Investigation and theNational Automobile Theft Bureau work through regional distributors. Onesource reports that an average of 2,365 automobiles are stolen everyday.

Some professional car thieves even provide the purchaser of the stolenvehicle with warranties to resteal the car if it turns out to have majordefects, so that a dissatisfied purchaser can collect the retail valuefrom his insurer. A great many of the vehicles which were stolen arestolen using the "hot wiring" or jumping of the ignition technique. Theautomatic electronic theft prevention or detection device portion of thepresent invention will eliminate this aspect of the problem. On theother hand, some highly organized and professional thieves utilizekey-making machinery which is concealed in a mobile panel truck. Thisaspect of the problem can be eliminated or solved by the electroniccombination lock device portion of the present invention.

SUMMARY OF THE INVENTION The present invention provides an apparatus ordevice for use in conjunction with a starting device for starting firstmeans, such as an engine, which requires electricity for operation. Theapparatus includes second means, such as a relay coil, having electricalinductance electrically connected between the starting device and thefirst means. The apparatus also includes third means, such as a diode,electrically connected in parallel with the second means. The thirdmeans has a substantially low impedance with respect to a flow ofelectrons in a predetermined direction and has a substantially lowadmittance with respect to a flow of electrons in a direction which isopposite to the mentioned predetermined direction. Fourth means, such asa resistor, provides an electrical path between the second means and areference potential. There is also included fifth means, such as relaycontacts functionally connected to an alarm device or an engine enablingdevice, operative in response to a flow of electrons through the secondmeans to prevent operation of the first means or to activate warningmeans.

The presentinvention also provides an electronic combination lock whichrequires a source of electrical power and a plurality of switchingelements, such as push button switches, having a first plurality ofterminals and a second plurality of terminals. The first means may beprovided for electrically connecting the source of electrical powerthrough at least one of the first (or second) plurality of terminals ofthe switching elements. The electronic combination lock also includes afirst electronic control device, such as a silicon-controlled rectifier,having a first terminal, a second terminal and a third terminal. Secondmeans electrically connects the first terminal of the electronic controldevice to the source of electrical power and to one of the second (orfirst) plurality of terminals associated with the first predeterminedone of the switching elements. A first impedance is connected betweenthe third terminal of the first electronic control device and anotherterminal of the second (or first) plurality of terminals associated withthe first predetermined switching element. A second impedance iselectrically connected between the third terminal of the firstelectronic control device and a reference potential, such as groundpotential. A third impedance is connected between the-second terminal ofthe first electronic control device and the reference potential. Asecond electronic control device, such as a silicon control rectifier,is provided having a first terminal, a second terminal and a thirdterminal. Third means electrically connects the source of electricalpower to the first terminal on the second electronic control device.Fourth means, which may include another electronic control device,electrically connects the second terminal of the first electroniccontrol device to the third terminal of the second electronic controldevice. A fourth impedance may be electrically connected between thesecond and third terminals of the second electronic control device.Fifth means, such as an indicator lamp or a resistor, electricallyconnects the second terminal of the second electronic control device tothe reference potential. A utilization device, which may include theparallel combination of a diode and a relay coil, may be electricallyconnected to the second terminal of the second electronic controldevice. The first electronic control device will be placed in aconductive condition only when the first predetermined switching elementis actuated. The second electronic control device will be placed in aconductive condition only if one of the plurality of switching elementsis actuated after or simultaneously with a predetermined one of saidswitching elements. Electrical power will be supplied to the utilizationdevice only when .the second electronic control device is in aconductive condition.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the circuitry of afirst embodiment of the present invention which can be employed as atheft prevention or detection device.

FIG. 2 illustrates a second embodiment of the present invention showingthe circuitry in an ignition protection embodiment.

FIG. 3 illustrates the third embodiment of the present invention showingthe circuitry in an ignition protection environment.

FIG. 4 illustrates a fourth embodiment of the present invention showingthe components of an electronic combination lock.

FIG. 5 illustrates a fifth embodiment of the present invention whichshows a modification of the preliminary modules of the FIG. 4 embodimentwherein the modification permits an individual digit of the combinationto be repeated.

DETAILED DESCRIPTION OF SOME PREFERRED EMBODIMENTS OF THE INVENTION Withreference to FIG. 1, there is shown a theft prevention or detectionapparatus or device for use in conjunction with a starting device forstarting first means, such as a vehicle engine, which requireselectricity for operation. Terminal 1 may be connected to the positiveterminal of a source of electricity, such as an automobile battery. Aconductor 2 connects the terminal 1 to a starting device 3, such as aconventional automobile ignition key switch or other locking device.

A conductor 12 connects the starting device to a terminal 11 which maybe, for example, electrically connected to the startersolenoid of anautomobile. An electrical conductor 13 connects the starting device 3 toa terminal 4. A conductor 14 electrically connects the terminal 4 to atenninal 15.

Second means, such as a relay coil 7, which includes electricalinductance is connected to terminal 15 and to a terminal 16. Thirdmeans, such as a diode 6, is also electrically connected betweenterminals 15 and 16 in parallel with the relay coil 7. A conductor 9connects the terminal 16 to a terminal 10 which may be conducted to thedistributor coil of the automobile engine.

Fourth means, such as a resistor 5, is connected between terminal 4 anda reference potential, such as ground potential.

Fifth means, such as relay contacts 17 and 18 associated with the relaycoil 7 and in conjunction with a suitable alarm device (not shown) or asuitable disabling device (not shown), is operative in response to aflow of electrons through the relay coil 7 to prevent operation of theengine or to activate the alarm device. The normally open relay contacts17 may be connected to terminals 19 and 20, and the normally closedrelay contacts 18 may be electrically connected to the terminals 20 and21.

The apparatus or device illustrated in FIG. 1 operates on the principlethat the direction of the flow of electrons can be differentiated anddetermined to be correct or incorrect. In the correct condition, whereelectrical power is supplied to the coil of an internal combustionengine through the ignition key switch 3, the electron flow will be fromterminal 10 to terminal 1. In that situation, the diode 6 offersvirtually no resistance to the flow of electrons, and consequentlyvirtually no voltage will be developed across the relay coil 7.

In the incorrect condition, such as when an attempt is made to jump orhot wire the engine, for example, by placing a jumper wire directly fromthe positive terminal 1 from the battery to terminal 10 of thedistributor coil, the diode 6 will block virtually all current flow witha very high resistance, thereby developing a voltage across relay coil 7which is sufficient to trip the relay. In that situation, the electronflow that transpires is from ground potential through the resistor 5,the relay coil 7 to terminal 10. With the actuation of the relay, anormally open set of contacts 17 or a normally closed set of contacts 18will be operated, or. a combination of them operated, to actuate anyalarm or disabling device, such as a siren, bell, horn, locking solenoidfor the brakes, steering gear, etc., which may be connected to theterminals 19, 20 or 21.

The embodiment illustrated in FIG. 1 operates automatically and does nothave to be set or engaged by the operator or driver in any way afterinstallation. Once installed, it operates whenever needed and does notinterfere with the normal operation of the vehicle in any manner.

The relay can be of the mechanical latching type; or can be wired with aconductor 22 connecting terminal 16 to a terminal 23 to be electricallyself-latching as shown in FIG. 1. If the electrical self-latchingarrangement is desired, terminal 20 may be connected to the positiveterminal of the battery.

If desired, all components within the dashed line 24 shown in FIG. 1 maybe constructed within a sturdy integral housing.

If desired, a capacitor 8 may be connected to terminals 15 and 16 inparallel with diode 6, but the capacitor 8 is not vital to successfuloperation of the apparatus.

The following sets forth exemplary values of the various components forautomotive use. Diode 6 may be a l N3889 diode or an equivalent. Therelay, comprising coil 7 and contacts l7 and 18, may be a GAl 1D orequivalent. The resistor 5 may be a lOO-ohm resistor, or an indicatorlamp'such as a GE 1488 or equivalent. The capacitor 8 may be a0.5-microfarad capacitor having a 600 direct current working voltagerating. It will be obvious to those skilled in the art that there is awide range of components which will operate satisfactorily in thedisclosed apparatus or device. It will also be obvious to those skilledin the art that the theft prevention or detection device may be used forautomotive, marine, or other vehicle engines which require electricalpower for operation.

FIG. 2 illustrates an alternative form of an apparatus for use inconjunction with a starting device for starting first means,

such as a vehicle engine, which requires electricity for operation. Asshown in FIG. 2, there is provided a starting device, such as ignitionswitch 34, which includes at least a first terminal 25, a secondterminal 26, a third terminal 27, a fourth terminal 28, a fifth terminal29, and a sixth terminal 30. If desired, the ignition switch 34 can alsoinclude a seventh terminal 31 which can be used for electricalconnection to the automobile accessories, and an eighth terminal 32. Theignition switch 34 also includes a rotary switching element 33 which iscapable of electrically connecting or bridging at least two of thevarious terminals of the ignition switch. The rotary switching element33 has a center post 35 which may be electrically connected by aconductor 36 to a terminal 37. The terminal 37 may be connected to asource of electrical power, such as the positive terminal of anautomobile battery.

First means, such as an automobile engine, is provided which includes adistributor coil 38 and a starter solenoid 39. The sixth terminal 30 ofthe ignition switch 34 may be electrically connected by a conductor 40to a first terminal 41 of the starter solenoid 39. Another terminal 42of the starter solenoid 39 may be connected to a source of referencepotential, such as ground potential.

The fifth terminal 29 on the ignition switch 34 may be electricallyconnected to a terminal 46 of the primary winding of the distributorcoil 38 via a conductor 43, a terminal 44 and a conductor 45.

The FIG. 2 embodiment also includes a first diode 52 and a second diode53 whose cathodes are electrically connected together at a terminal 54.The fourth terminal 28 of the ignition switch 34 is electricallyconnected to the anode of the first diode 52. A first impedance, such asa resistor 55, is electrically connected between the second terminal 26of the i gnition switch 34 and the anode of the second diode 53. Asecond impedance, such as a resistor 56, is electrically connectedbetween terminals 44 and 54.

There is also shown an electronic control device, such as a siliconcontrol rectifier 57, whose anode is electrically connected to the firstterminal 25 of the ignition switch 34. A relay coil 59 is electricallyconnected between the cathode of the silicon control rectifier. 57 and areference potential, such as ground potential. Sixth means, such as aresistor 58, may be electrically connected between the anode of thesecond diode 53 and the gate element of the silicon control rectifier57.

A third impedance may comprise a resistor 49 which is electricallyconnected across the breaker points 60 from ground potential to a secondterminal 48 of the primary winding 47 of the distributor coil 38.Alternatively, the third impedance element may comprise a resistor 50which is connected between the terminal 48 of the primary winding 47 tothe ground terminal 61 of the secondary winding 51 of the distributorcoil 38. It is not necessary to employ both resistors 49 and 50, aseither one will sufi'rce.

The apparatus or ignition protection system depicted in FIG. 2 isdesigned to detect or prevent any attempt to hot wire the electricalsystem of any electrical or internal combustion engine, and to detectthe removal of the ignition wire and an attempt to circumvent an alarmsystem prior to hot wiring the system. The presentation of the batteryvoltage at terminal 25, as well as any interruption of the voltagedivider network consisting of resistor 55, resistor 56, the distributorcoil primary winding 47, and resistor 49 (or resistor 50), will actuateany alarm and/or disabling device (not shown) which may be operativelyconnected to the relay contacts 62 associated with the relay coil 59.

Electrical power is applied to the FIG. 2 embodiment by means of specialconnections within the ignition key switch 34 so that power is appliedonly when the key is in the off position. The logic of the ignitionswitch is all explained below.

When the rotary switching element 33 bridges the terminals 31 and 32,this will be deemed as accessories only position. When the rotaryswitching element 33 bridges terminals 25 and 26, this will be deemed analarm engaged position. When the rotary switching element 33 bridges theterminals 27 and 28, this will be deemed an on position. When the rotaryswitching element 33 bridges the terminals 28 and 29 during a momentarycontact, this will be deemed an interim shorting position. When therotary switching element 33 bridges the terminals 29 and 30, this willbe deemed the start momentary contact position.

When the engine is on or operating, the apparatus according to thepresent invention is in an off condition. The operator or driver neednot remember to consciously do some special act to engage the alarm ordisabling device.

The battery voltage applied to the above-mentioned voltage dividernetwork which provides a very low voltage reference potential atterminal 63, which is shown as being interposed between resistor 55 andthe anode of the second diode 53.

ln the event that either a jumper wire is employed to provide a batteryvoltage at terminal 46 or if the ignition wire is removed at terminal 66or at terminal 56 to interrupt the circuit, then the reference voltageat terminal 63 will rise to approximately the positive battery voltage.This last mentioned voltage or potential will act on the gate element ofthe silicon control rectifier 57 through the resistor 58, which may bedeemed a limiting resistor, to turn on the rectifier 57 which in turnwill actuate the relay consisting of coil 59 and contact 62 for whateveralarm or disabling device is connected thereto. The silicon controlrectifier 57 will then remain on or in a conductive position until theapparatus is reset by means of the ignition key switch 34 being turnedto its on position.

it should be noted that this embodiment of the present invention isreadily adapted to present day automobiles for the following reasons.The resistor 56 is the normal dropping resistor which is found in allautomobiles having a l2-volt system. It should also be noted thatresistor 49 or resistor 50 will be out of the circuit when the engine isstopped at a point when the breaker points 60 are closed. The resistor49 could be added to ignition systems which have not been built withthis device. The resistor 50 can readily be a resistor which is builtinto the molded plastic coil housing for the built-in apparatusaccording to the present invention. Various integral housings or pottedenclosures can of course be employed to house various combinations ofthe components illustrated in FIG. 2.

Some exemplary component values for the FIG. 2 embodiment are asfollows. Resistor 55 may be a 1,200-ohm resistor. Resistor 58 may be aZOO-ohm resistor. Resistor 49 or resistor 50may be a 60-ohm resistor.The silicon control rectifier 57 may be a C106Y1 rectifier. The diodes52 and 53 may be of the 1N3889 type and lN4004 type, respectively. Therelay consisting of coil 59 and its associated contacts 62 may be anyappropriate relay coil operating at 12 volts at direct current.

if desired, a buffer transistor amplifier may be interposed betweenterminal 63 and the gate element of the rectifier 57 in lieu of theresistor 58.

The diode 52 will be required only if the switch 34 does not separatethe accessory circuit from the ignition circuit when it is in the offposition.

A third embodiment of the present invention is illustrated in FIG. 3which also shows an apparatus for use in conjunction with a startingdevice, such as an automobile ignition switch, for starting first means,such as an automobile engine, which requires electricity for operation.The starting device or ignition switch includes at least a firstterminal 70, a second terminal 73, and a third terminal 74. A source ofelectrical power, such as an automobile battery (not shown), may beconnected to the first terminal 70 of the ignition switch. The apparatusalso includes a first diode 75, a second diode 76, and a third diode 77.There is also provided two electronic control devices, such as a firsttransistor 78 and a second transistor 79. Another electronic controldevice, taking the form of a silicon control rectifier 80, is alsoprovided in the apparatus.

The second terminal 73 of the ignition switch is electrically connectedto the anode of the diode 75, and the cathode of the diode 75 iselectrically connected to the cathode of the diode 76 via a commonterminal 81. A first impedance element, such as a resistor 82, isconnected between the first terminal 70 (which is connected to thepositive terminal of the automobile battery) and the anode of the seconddiode 76.

A second impedance element, such as a resistor 83, is electricallyconnected between the terminal 81 and the third terminal 74 of theignition switch. The third terminal 74 of the ignition switch may beconsidered the engine starting position of the ignition switch. Theterminal 74 may be electrically connected to a first terminal 84 of aprimary winding 85 of a distributor coil 86 of the engine. A secondarywinding 87 of the distributor coil 86 may have one of its terminals,such as 88, electrically connected to a reference potential, such asground potential. A third impedance element, such as resistor 89, may beconnected between a second terminal 90 of the primary winding 85 andterminal 88 of the secondary winding 87.

A fourth impedance, such as a resistor 91, may be connected betweenterminal 72 and the collector of the first transistor 78. A fifthimpedance, such as a resistor 92, may be electrically connected betweenthe collector of the transistor 78 and the base of the second transistor79.

A sixth impedance, such as a resistor 93, may be electrically connectedbetween the collector of transistor 79 and ground potential.

The anode of the silicon control rectifier 80 may be electricallyconnected to terminal 72. A relay coil 94 may have one of its terminalsconnected to the cathode of the silicon control rectifier 80 and haveits other terminal connected to ground potential. The capacitor may beconnected between the gate of the silicon control rectifier 80 andground potential.

A seventh impedance, such as a resistor 96, may be connected between thegate of the silicon control rectifier 80 and the collector of the secondtransistor 79.

An eighth impedance, such as a resistor 97, may be electricallyconnected between terminal 72 and the collector of the first transistor78. The cathode of the third diode 77 may be electrically connected tothe emitter of the first transistor 77, and the anode of diode 77 may beelectrically connected to ground potential.

A ninth impedance, such as a resistor 98, may have one of its terminalsconnected to the base of transistor 78 and the other of its terminals,designated 99, movably slidable along the resistor 82.

Fifth means, comprising the relay coil 94, its associated contacts 100,and any alarm and/or disabling device operatively connected to contacts100, are provided to operate in response to a flow of electrons throughthe relay coil 94 to prevent operation of the engine and to activate thementioned alarm device or other warning means.

The third embodiment of the invention illustrated in F IG. 3 is designedto detect and actuate a relay, consisting of coil 94 and contacts 100,or any other sensing device whenever a hot wire jumper is employed by awould-be thief to start a vehicle engine, or whenever the ignition wireis removed prior to the hot wiring attempt to start, or in the eventthat these detections of an unauthorized start of the vehicle arecircumvented, any starting of the vehicle engine while the apparatus isoperative or engaged. From the foregoing, it can be appreciated that theinventive apparatus will minimize if not completely eliminate the theftof vehicles employing engines requiring electricity.

In the third embodiment of the invention, the conventional automotiveignition system, consisting of an ignition switch, the dropping resistor83, the distributor coil 86, and breaker points 101, is first altered bythe addition of the diode 75 which isolates the automobile accessoriesfrom the remainder of the system. Essentially, the inventive apparatusis connected to the system at terminal 81 which can be located in anarea which is quite inaccessible to thieves, such as within a pottedenclosure with diode 75 and various other components of the novelapparatus.

If desired, a switch 71 may be provided as a separate switch,

75 or part of the ignition switch which is closed when the ignitionswitch is in the'ofi position. The optional switch 71 may provideelectrical power from the battery to the apparatus. as well as areference voltage to terminal 72 of a voltage divider network consistingof potentiometer or resistor 82, the diode 76, the dropping resistor 83,the primary winding 85 of the distributor coil, and the resistor 89(unless of course the breaker points 101 are closed when the vehicleengine stops, whereby resistor 89 will be out of the circuit, shorted bythe breaker points 101).

The sliding terminal 99 is adjusted to provide a reference voltage atterminal 99 which is slightly more negative than the voltage at theemitter of transistor 78, thereby biasing the transistor 78 to an off ornonconductive condition. The resistor 98 limits the base current oftransistor 78 to within the rated limits when transistor 89 isconducting. The diode 77 cooperates with the resistor 91 to provide astable reference for the emitter of transistor 78. The transistor 78will be turned on if the voltage at terminal 99 rises due to a hot wireor jumper being applied at terminal 84, or the voltage at terminal 72rising due to the alternator being engaged by the starting motor.

When transistor 78 fires or changes to a conductive position, thevoltage change at the collector of transistor 78 fires or turns on thetransistor 79. The transistor 79 acts through resistor 96 to fire orturn the silicon control rectifier 80, thereby actuating an alarm and/orrelay which engages the actual alarms or disabling devices. Thecapacitor 95 provides a slight time delay for the rectifier 80 in orderto prevent a false alarm when the apparatus is initially switched on.

The diode 75 blocks current flow through the accessories to cut off thevoltage divider network. The diode 76 blocks current flow when theapparatus is off and the engine is on in order to protect the apparatusand particularly transistor 78 from damage.

The resistor 89 should be added to the conventional ignition circuitacross the breaker points 101 to provide a complete circuit to groundpotential to accommodate the situation which occurs when the enginestops and the breaker points 101 are open. The resistor 89 would beshorted out by the breaker points when the engine stops with the breakerpoints 101 closed.

The third embodiment of the present invention is thus seen to be voltagelevel sensitive, as well as sensitive to other major changes, such as ajumper wire from the battery to terminal 84, or the breaking of theintegrity of the automotive ignition system.

With reference to FIG. 4, there is shown a fourth embodiment of thepresent invention in the form of a novel electronic combination lock.This electronic combination lock utilizes the self-latchingcharacteristics of the thyristor family of semiconductors, and theembodiment illustrated in FIG. 4 employs silicon controlled rectifiers111, 112 and 113, in a form suitable for the control or protection of anautomotive or marine electrical system.

FIG. 4 depicts a three-stage electronic sequential combination lockwhich is shown wired for the combination 4397. The designation 39indicates that the No. 3 pushbutton and the No. 9 pushbutton must bedepressed simultaneously, and this is identical to the designation 93.

A positive voltage is applied at terminal 110 from a source ofelectrical power, such as an automobile battery (not shown). For thewired combination 4-39-7, when the switching element or pushbutton No. 4is depressed, then the silicon control rectifier 111 will be turned onand will maintain conduction even after pushbutton No. 4 returns to itsnormal or home position as illustrated in FIG. 4.

The silicon control rectifier 111 then provides a positive voltage atits cathode, which is then used, by depressing pushbutton No. 3 andpushbutton No. 9 simultaneously, to provide a turn on voltage to thegate of a silicon control rectifier 112. The silicon control rectifier112 then maintains its conduction which provides a voltage at itscathode which enables a silicon control re'ctifier 1 13 to be turned onwhen a pushbutton No. 7 is depressed.

The silicon control rectifier 113 must have a capacity which is capableof passing sufficient electrical current to operate a load device whichmay be electrically connected to a terminal 1 14 and/or a terminal 115.For example, the terminal 114 may be electrically connected to thestarter solenoid of an automobile, and the terminal 115 may be connectedto the engine and accessories of an automobile. When a switch, such as aswitch 116, is depressed, for example, to actuate the starter solenoidof an automobile, then the preliminary stages of the electronicsequential combination lock are turned off in order to minimize thecurrent drain and prolong the life of the components.

If an incorrect pushbutton switch is depressed during the sequentialcombination attempt, then the preliminary stages of the electroniccombination lock are turned off by depriving them of electrical current,and the combination must be started again. If desired, there may beprovided an of switch, such as a switch 117, which turns off the devicewhen it is depressed at any time. The switch 117 may also serve toautomatically reset the combination.

The portions of the embodiment illustrated in FIG. 4 within the phantomlines indicated by the reference numerals 118 and 119 may be consideredas integer modules. One module must be used for each individual numberof the combination. A multiple digit number in the combination, such as39, or 321, etc., would be considered or counted as an individual numberin the combination. The size of the combination and its complexity canbe expanded or contracted by adding or deleting, respectively, integermodule stages.

With respect to the module 118, the silicon control rectifier 111 may beconsidered to be an electronic control device or may be considered to bea device which is controlled. In any event, the silicon controlrectifier 111 is turned on by the application of an appropriate voltageat its gate when there is also an appropriate voltage applied to itsanode. A first impedance, such as a resistor 120, serves to limit thegate current to within rated levels for the silicon control rectifier111. A second impedance, such as a resistor 121, serves as the secondleg of a voltage divider network in order to develop sufficient voltageto turn on the silicon control rectifier 111. A third impedance, such asa resistor 122, limits the on" state current to within rated levels, andtypically allows only sufficient current to maintain a latched state inthe on condition.

The module 119 may be an exact duplicate of the module 1 18.

The plurality of switching elements, such as pushbuttons No. 1 throughNo. 10, are wired in FIG. 4 in such a way as to provide normally opencontacts for each module as desired, and normally closed contacts forthe disengaged circuit for incorrect numbers. Of course, this wiringarrangement may be reversed, with respect to the normally open andnormally closed contacts, and such a reversed wiring arrangement isillustrated in FIG. 5.

With reference to FIG. 4, the final stage, such as the silicon controlrectifier 113, is similar to the modules 118 and 119 with the majorexception that a fourth impedance, such as a resistor 123, iselectrically connected between the cathode and the gate of the rectifier113 to prevent a negative voltage from being employed to turn on thedevice. A fifth means, such as an indicator lamp 124, may serve as anelectrical path for the minimum latching current, as well as an onindicator for the complete device. If desired, the indicator lamp 124may be replaced by a resistor. Also, if desired, the module 125 enclosedin phantom lines in FIG. 4 may be similar to the automatic theftdetector apparatus illustrated in FIG. 1.

The terminology used in some of the appended claims such as a fifthimpedance, a sixth impedance, a seventh impedance and an eighthimpedance may refer to resistors 126, 127, 128 and 129, respectively, asshown in FIG. 4. The cathode of the silicon control rectifier has beenindicated as a terminal 130 for reasons which will become apparent inthe following description of the fifth embodiment of the invention shownin FIG. 5. The selection of the various components illustrated in FIG. 4is not critical. An exemplary component selection for the embodimentshown in FIG. 4 may be as follows. The resistors 120 and 126 may beSOO-ohm resistors with a -watt rating. The resistors 121 and 127 may beZOO-ohm resistors with a A-watt rating. The resistors 122 and 128 may be1,000- ohm resistors having a -watt rating. The resistor 129 may be alOO-ohm resistor with a l-watt rating. The resistor 123 may be a 50-ohmresistor with a /z-watt rating. The silicon controlled rectifiers 111and l 12 may be of the ClO6Yl type. The silicon control rectifier 1 13may be of the 2N682 type. The indicator lamp 124 may be a GEl488 lamp.The various pushbutton switches No. 1 through No. 10 may be anydouble-pole double-throw switches which have suitable current capacity.In the off state, the device will draw minimum current typically lessthan 5 microamperes, and in the on state the device will pass sufficientcurrent with less than 0.6 voltage drop across the silicon controlrectifier 113.

A fifth embodiment of the present invention is illustrated in FIG. 5.The FIG. 5 is actually a partial or truncated schematic of thepreliminary modules which employ a wiring arrangement that allows anindividual number in the combination to be repeated. In particular,thewiring arrangement shown is for the combination 2-1-2. Some of thecomponents illustrated in FIG. 5 which are identical to components shownin FIG. 4, are indicated by like reference numerals. Similarly, theportions of FIG. 5 within the phantom lines indicated by the referencenumerals 131, 132, and ll33 are the integer modules. The terminal 130shown in FIG. 5, as with the terminal 130 illustrated in FIG. 4, wouldlead or be electrically connected to the final number in the combinationfor the last stage of the electronic combination lock.

It is important to note that the final stage electronic control device,for example, the silicon controlled rectifier 57 in the secondembodiment, or the silicon control rectifier 80 in the third embodiment,or the silicon controlled rectifier 113 in the fourth embodiment, neednot necessarily be electronically connected to a relay coil orrelaydevice. In other words, it is possible to utilize the inventive conceptherein disclosed without the necessity of a relay electrically connectedto the final stage electronic device by having the final stageelectronic control device directly actuate any desired warning means,disabling device or alarm mechanism.

The electronic sequential combination lock illustrated in FIGS. 4 and 5,and any variations or modifications thereof, can of course be used formany other applications or jobs, such as a door lock, an ignition lockfor all types of vehicles, a cryptographic lock for security areas, anignition lock for marine use, a machinery lock, etc.

It should also be noted that the novel electronic combination lockdisclosed hereincan be utilized to control a plurality of other devices.For example, one of the novel electronic combination locks can be wiredto control thirty other devices.

The electronic combination lock can also be used in other areas, such asmail boxes for apartment houses, and dispensing units. In essence, theinvention provides a novel switch which can replace any other switchingdevice now in use.

According to the invention, the matrix selected for the combination lockmay permit tens tests of millions of variations in the combination.Also, a time limitation feature can easily be included in the inventivecombination lock to require the completion of the combination within apredetermined time interval, e.g., seconds, but this is not mandatory.Moreover, the novel electronic combination lock can be manufactured inthe form of a secure potted-type of unit to maintain the integrity ofthe lock and to minimize the possibility of an individual tracing thewiring in an attempt to learn the combination.

lclaim:

ll. Apparatus for use in conjunction with a starting device for startingfirst means which requires electricity for operation, comprising, incombination:

second means including electrical inductance electrically connectedbetween said starting device and said first means;

third means electrically connected in parallel with said second means;

said third means having a substantially low impedance with respect to aflow of electrons in a predetermined direction and having asubstantially low admittance with respect to a flow of electrons in adirection which is opposite to said predetermined direction;

fourth means providing an electrical path between said second means anda reference potential; and

fifth means operative in response to a flow of electrons through saidsecond means to prevent operation of said first means or to activatewarning means.

2. Apparatus characterized in accordance with claim 1, wherein saidfirst means comprises a vehicle engine including a coil; said startingdevice has a first terminal electrically connected to a source ofelectricity, and a second terminal electrically connected to said secondmeans; said second means comprises a relay coil; said third meanscomprises a diode which is connected between said second terminal ofsaid starting device and said coil of said vehicle engine; and saidfourth means comprises a resistor connected between said second terminalof said starting device and ground potential.

3. Apparatus for use in conjunction with a starting device for startingfirst means which requires electricity for operation, comprising, incombination:

said starting device including at least a first terminal, a

second terminal, a third terminal, a fourth terminal, a fifth terminaland a sixth terminal, and a rotary switching element which is capable ofbridging at least two of said terminals and having its center postelectrically connected to a source of electrical power;

said first means comprising a vehicle engine including a distributorcoil and a starter solenoid;

said sixth terminal of said starting device being electrically connectedto said starter solenoid;

said fifth terminal of said starting device being electrically connectedto said distributor coil; a first diode; a second diode; a relay coil; asilicon controlled rectifier; a first impedance element; a secondimpedance element; a third impedance element; said relay coil beingconnected between a reference potential and the cathode of saidsilicon-controlled rectifier;

said first terminal of said starting device being electrically connectedto the anode of said silicon-controlled rectifisaid first and seconddiodes having their cathodes electrically connected together;

said fourth terminal of said starting device being electricallyconnected to the anode of said first diode;

said second impedance element being electrically connected between thecathodes of said diodes and the distributor coil;

said first impedance element being connected between said secondterminal of said starting device and the anode of said second diode;

sixth means electrically connected between the anode of said seconddiode and the gate element of said siliconcontrolled rectifier;

said third impedance element being connected between a referencepotential and the primary winding of said distributor coil;

and fifth means operative in response to a flow of electrons throughsaid relay coil to prevent operation of said first means or to activatewarning means.

4. Apparatus characterized in accordance with claim 3, wherein saidsixth means includes a resistor electrically connected between the gateelement of said silicon-controlled rectifier and the anode of saidsecond diode.

5. Apparatus characterized in accordance with claim 3, wherein saidsixth means includes an amplifier electrically connected between thegate element of said silicon-controlled rectifier and said anode of saidsecond diode.

6. Apparatus characterized in accordance with claim 3, wherein saidthird impedance element includes a resistor electrically connectedbetween a reference potential and the primary winding of saiddistributor coil.

7. Apparatus characterized in accordance with claim 3, wherein saidthird impedance element includes a resistor having one terminalconnected to the primary winding of said distributor coil and havinganother terminal connected to the grounded terminal of the secondarywinding of said distributor coil.

8. Apparatus for use in conjunction with a starting device for startingfirst means which requires electricity for operation, comprising, incombination:

said starting device including at least a first terminal, a

second terminal and a third terminal;

a source of electrical power which is connected to said first terminalof said starting device;

a first diode, a second diode, and a third diode;

a first transistor and a second transistor, each of said transistorshaving a first terminal, a second terminal and a third terminal 1;

said first means comprising a vehicle engine including a distributorcoil;

a silicon controlled rectifier having a cathode element, an

anode element, and a gate element;

said second terminal of said starting device being electricallyconnected to the anode of said first diode;

said first diode having its cathode electrically connected to thecathode of said second diode;

a first impedance element connected between said first terminal of saidstarting device and the anode of said second diode;

a second impedance element electrically connected from the cathodes ofsaid first and second diode to said third terminal of said startingdevice;

said third terminal of said starting device being electrically connectedto a first terminal of a primary winding of said distributor coil;

the secondary winding of said distributor coil having one of itsterminals electrically connected to a reference potential;

a third impedance element connected between a second terminal of saidprimary winding of said distributor coil and said one terminal of saidsecondary winding of said dis tributor coil;

a fourth impedance electrically connected between said first terminal ofsaid starting device and said third terminal of said first transistor;

a fifth impedance electrically connected between said first terminal ofsaid first transistor and said second terminal of said secondtransistor;

a sixth impedance connected between said third terminal of said secondtransistor and said reference potential;

said anode element of said silicon-controlled rectifier beingelectrically connected to said first terminal of said starting device;

means connecting said cathode element of said silicon-controlledrectifier to said reference potential;

a capacitor connected between said gate element of saidsilicon-controlled rectifier and said reference potential;

a seventh impedance connected between said gate element of saidsilicon-controlled rectifier and said third terminal of said secondtransistor;

an eighth impedance connected between said first terminal of saidstarting device and said first terminal of said first transistor;

said third diode having its cathode electrically connected to said thirdterminal of said first transistor and having its anode electricallyconnected to said reference potential;

a ninth impedance having one of its terminals connected to said secondterminal of said first transistor and having the other of its terminalsmovably slidable along said first impedance; and

fifth means operative to a conductive condition of saidsilicon-controlled rectifier to prevent operation of said first means orto activate warning means.

9. An electronic combination lock comprising, in combination:

a source of electrical power;

a plurality of switching elements having a first plurality of terminalsand a second plurality of terminals;

first means for electrically connecting said source of electrical powerto at least one of said first plurality of terminals of said switchingelements;

a first electronic control device having a first terminal, a

second terminal and a third terminal;

second means electrically connecting said first terminal of saidelectronic control device to said source of electrical power and to oneof said second plurality of terminals associated with a firstpredetermined one of said switching elements;

a first impedance connected between said third terminal of said firstelectronic control device and another terminal of said second pluralityof terminals associated with said first predetermined switching element;

a second impedance electrically connected between said third terminal ofsaid first electronic control device and a reference potential;

a third impedance connected between said second terminal of said firstelectronic control device and said reference potential;

a second electronic control device having a first terminal, a

second terminal and a third terminal;

third means electrically connecting said source of electrical power tosaid first terminal of said second electronic control device;

fourth means electrically connecting said second terminal of said firstelectronic control device to said third terminal of said secondelectronic control device;

a fourth impedance electrically connected between said second terminalof said second electronic control device and said third terminal of saidsecond electronic device;

a fifth means electrically connecting said second terminal of saidsecond electronic control device -to said reference potential;

a utilization device electrically connected to said second terminal ofsaid second electronic control device;

and whereby said first electronic control device will be placed into aconductive condition only when said first predetermined switchingelement is actuated, and whereby said second electronic control devicewill be placed into a conductive condition only if one of said pluralityof switching elements is actuated after or simultaneously with firstpredetermined one of said switching elements, and whereby electricalpower will be supplied to said utilization device only when said secondelectronic control device is in a conductive condition.

10. An electronic combination lock characterized in accordance withclaim 9, wherein said utilization device comprises a starting device forstarting sixth means which requires electricity for operation, andincluding:

seventh means having electrical inductance electrically connectedbetween said starting device and said sixth means;

eighth means electrically connected in parallel with said seventh means;

said eighth means having a substantially low impedance with respect to aflow of electrons in a predetermined direction and having asubstantially low admittance with respect to a flow of electrons in adirection which is opposite to said predetermined direction;

and ninth means operative in response to a flow of electrons throughsaid seventh means to prevent operation of said sixth means or toactivate warning means.

11. An electronic combination lock characterized in accordance withclaim 9, wherein said fourth means includes:

a third electronic control device having a first terminal, a

second terminal, and a third terminal;

said second means electrically connecting said first terminal of saidthird electronic control device to said source of electrical power andto at least one of said first or second plurality of terminals of saidswitching elements;

a fifth impedance electrically connected between said third terminal ofsaid third electronic control device and one of said second plurality ofterminals associated with a second predetermined one of said switchingelements;

sixth means electrically connected to another one of said secondplurality of terminals associated with said second predeterminedswitching element to said second terminal of said first electroniccontrol device;

sixth impedance electrically connected between said third terminal ofsaid third electronic control device and said reference potential;

a seventh impedance electrically connected between said second terminalof said third electronic control device of said third electronic controldevice and said reference potential;

a first electrical conductor connected between said second terminal ofsaid third electronic control device and one of said second plurality ofterminals associated with a third predetermined one of said switchingelements;

and an-eighth impedance electrically connected between said thirdterminal of said second electronic control device and another terminalof said second plurality of terminals associated with said thirdpredetermined one of said switching elements.

12. An electronic combination lock characterized in accordance withclaim 9, wherein said fourth means includes:

a third electronic control device having a first terminal, a

second terminal, and a third terminal:

a fourth electronic control device having a first terminal, a

second terminal, and a third terminal;

said second terminal of said first electronic control device beingelectrically connected to one of said second plurality of terminalsassociated with one of said switching elements;

an impedance electrically connected between said third terminal of saidthird electronic control device and one of said second plurality ofterminals associated with said one switching element;

an impedance electrically connected between said third terminal of saidthird electronic control device and said reference potential;

an impedance electrically connected between said second terminal of saidthird electronic control device and said reference potential;

an impedance electrically connected between said second tenninal of saidthird electronic control device and said third terminal of said fourthelectronic control device;

an impedance electrically connected between said second terminal of saidfourth electronic control device and said reference potential;

an impedance electrically connected between said third terminal of saidfourth electronic control device and said reference potential;

said third terminal of said fourth electronic control device beingelectrically connected to one of said first plurality of terminalsassociated with said first predetermined switching element;

another one of said first plurality of terminals associated with saidfirst predetermined switching element being electrically connected tosaid reference potential;

said second terminal of said fourth electronic control device beingelectrically connected to one of said second plurality of terminalsassociated with a second predetermined switching element;

an impedance electrically connected between said third terminal of saidsecond electronic control device and another of said second plurality ofterminals associated with said second redeter 'nined switching element;and wherein said lrst terminal of said first electronic control device,said first terminal of said second electronic control device, said firstterminal of said third electronic control device, and said firstterminal of said fourth electronic control device are all electricallyconnectable to said source of electrical power.

1. Apparatus for use in conjunction with a starting device for startingfirst means which requires electricity for operation, comprising, incombination: second means including electrical inductance electricallyconnected between said starting device and said first means; third meanselectrically connected in parallel with said second means; said thirdmeans having a substantially low impedance with respect to a flow ofelectrons in a predetermined direction and having a substantially lowadmittance with respect to a flow of electrons in a direction which isopposite to said predetermined direction; fourth means providing anelectrical path between said second means and a reference potential; andfifth means operative in response to a flow of electrons through saidsecond means to prevent operation of said first means or to activatewarning means.
 2. Apparatus characterized in accordance with claim 1,wherein said first means comprises a vehicle engine including a coil;said starting device has a first terminal electrically connected to asource of electricity, and a second terminal electrically connected tosaid second means; said second means comprises a relay coil; said thirdmeans comprises a diode which is connected between said second terminalof said starting device and said coil of said vehicle engine; and saidfourth means comprises a resistor connected between said second terminalof said starting device and ground potential.
 3. Apparatus for use inconjunction with a starting device for starting first means whichrequires electricity for operation, comprising, in combination: saidstarting device including at least a first terminal, a second terminal,a third terminal, a fourth terminal, a fifth terminal and a sixthterminal, and a rotary switching element which is capable of bridging atleast two of said terminals and having its center post electricallyconnected to a source of electrical power; said first means comprising avehicle engine including a distributor coil and a starter solenoid; saidsixth terminal of said starting device being electrically connected tosaid starter solenoid; said fifth terminal of said starting device beingelectrically connected to said distributor coil; a first diode; a seconddiode; a relay coil; a silicon controlled rectifier; a first impedanceelement; a second impedance element; a third impedance element; saidrelay coil being connected between a reference potential and the cathodeof said silicon-controlled rectifier; said first terminal of saidstarting device being electrically connected to the anode of saidsilicon-controlled rectifier; said first and second diodes having theircathodes electrically connected together; said fourth terminal of saidstarting device being electrically connected to the anode of said firstdiode; said second impedance element being electrically connectedbetween the cathodes of said diodes and the distributor coil; said firstimpedance element being connected between said second terminal of saidstarting device and the anode of said second diode; sixth meanselectrically connected between the anode of said second diode and thegate element of said silicon-controlled rectifier; said third impedanceelement being connected between a reference potential and the primarywinding of said distributor coil; and fifth means operative in responseto a flow of electrons through said relay coil to prevent operation ofsaid first means or to activate warning means.
 4. Apparatuscharacterized in accordance with claim 3, wherein said sixth meansincludes a resistor electrically connected between the gate element ofsaid silicon-controlled rectifier and the anode of said second diode. 5.Apparatus characterized in accordance with claim 3, wherein said sixthmeans includes an amplifier electrically connected between the gateelement of said silicon-controlled rectifier and said anode of saidsecond diode.
 6. Apparatus characterized in accordance with claim 3,wherein said third impedance element includes a resistor electricallyconnected between a reference potential and the primary winding of saiddistributor coil.
 7. Apparatus characterized in accordance with claim 3,wherein said third impedance element includes a resistor having oneterminal connected to the primary winding of said distributor coil andhaving another terminal connected to the grounded terminal of thesecondary winding of said distributor coil.
 8. Apparatus for use inconjunction with a starting device for starting first means whichrequires electricity for operation, comprising, in combination: saidstarting device including at least a first terminal, a second terminaland a third terminal; a source of electrical power which is connected tosaid first terminal of said starting device; a first diode, a seconddiode, and a third diode; a first transistor and a secOnd transistor,each of said transistors having a first terminal, a second terminal anda third terminal l; said first means comprising a vehicle engineincluding a distributor coil; a silicon controlled rectifier having acathode element, an anode element, and a gate element; said secondterminal of said starting device being electrically connected to theanode of said first diode; said first diode having its cathodeelectrically connected to the cathode of said second diode; a firstimpedance element connected between said first terminal of said startingdevice and the anode of said second diode; a second impedance elementelectrically connected from the cathodes of said first and second diodeto said third terminal of said starting device; said third terminal ofsaid starting device being electrically connected to a first terminal ofa primary winding of said distributor coil; the secondary winding ofsaid distributor coil having one of its terminals electrically connectedto a reference potential; a third impedance element connected between asecond terminal of said primary winding of said distributor coil andsaid one terminal of said secondary winding of said distributor coil; afourth impedance electrically connected between said first terminal ofsaid starting device and said third terminal of said first transistor; afifth impedance electrically connected between said first terminal ofsaid first transistor and said second terminal of said secondtransistor; a sixth impedance connected between said third terminal ofsaid second transistor and said reference potential; said anode elementof said silicon-controlled rectifier being electrically connected tosaid first terminal of said starting device; means connecting saidcathode element of said silicon-controlled rectifier to said referencepotential; a capacitor connected between said gate element of saidsilicon-controlled rectifier and said reference potential; a seventhimpedance connected between said gate element of said silicon-controlledrectifier and said third terminal of said second transistor; an eighthimpedance connected between said first terminal of said starting deviceand said first terminal of said first transistor; said third diodehaving its cathode electrically connected to said third terminal of saidfirst transistor and having its anode electrically connected to saidreference potential; a ninth impedance having one of its terminalsconnected to said second terminal of said first transistor and havingthe other of its terminals movably slidable along said first impedance;and fifth means operative to a conductive condition of saidsilicon-controlled rectifier to prevent operation of said first means orto activate warning means.
 9. An electronic combination lock comprising,in combination: a source of electrical power; a plurality of switchingelements having a first plurality of terminals and a second plurality ofterminals; first means for electrically connecting said source ofelectrical power to at least one of said first plurality of terminals ofsaid switching elements; a first electronic control device having afirst terminal, a second terminal and a third terminal; second meanselectrically connecting said first terminal of said electronic controldevice to said source of electrical power and to one of said secondplurality of terminals associated with a first predetermined one of saidswitching elements; a first impedance connected between said thirdterminal of said first electronic control device and another terminal ofsaid second plurality of terminals associated with said firstpredetermined switching element; a second impedance electricallyconnected between said third terminal of said first electronic controldevice and a reference potential; a third impedance connected betweensaid second terminal of said first electronic control device and saidreference potential; a second electronic control device having a firstterminal, a second terminal and a third terminal; third meanselectrically connecting said source of electrical power to said firstterminal of said second electronic control device; fourth meanselectrically connecting said second terminal of said first electroniccontrol device to said third terminal of said second electronic controldevice; a fourth impedance electrically connected between said secondterminal of said second electronic control device and said thirdterminal of said second electronic device; a fifth means electricallyconnecting said second terminal of said second electronic control deviceto said reference potential; a utilization device electrically connectedto said second terminal of said second electronic control device; andwhereby said first electronic control device will be placed into aconductive condition only when said first predetermined switchingelement is actuated, and whereby said second electronic control devicewill be placed into a conductive condition only if one of said pluralityof switching elements is actuated after or simultaneously with firstpredetermined one of said switching elements, and whereby electricalpower will be supplied to said utilization device only when said secondelectronic control device is in a conductive condition.
 10. Anelectronic combination lock characterized in accordance with claim 9,wherein said utilization device comprises a starting device for startingsixth means which requires electricity for operation, and including:seventh means having electrical inductance electrically connectedbetween said starting device and said sixth means; eighth meanselectrically connected in parallel with said seventh means; said eighthmeans having a substantially low impedance with respect to a flow ofelectrons in a predetermined direction and having a substantially lowadmittance with respect to a flow of electrons in a direction which isopposite to said predetermined direction; and ninth means operative inresponse to a flow of electrons through said seventh means to preventoperation of said sixth means or to activate warning means.
 11. Anelectronic combination lock characterized in accordance with claim 9,wherein said fourth means includes: a third electronic control devicehaving a first terminal, a second terminal, and a third terminal; saidsecond means electrically connecting said first terminal of said thirdelectronic control device to said source of electrical power and to atleast one of said first or second plurality of terminals of saidswitching elements; a fifth impedance electrically connected betweensaid third terminal of said third electronic control device and one ofsaid second plurality of terminals associated with a secondpredetermined one of said switching elements; sixth means electricallyconnected to another one of said second plurality of terminalsassociated with said second predetermined switching element to saidsecond terminal of said first electronic control device; sixth impedanceelectrically connected between said third terminal of said thirdelectronic control device and said reference potential; a seventhimpedance electrically connected between said second terminal of saidthird electronic control device of said third electronic control deviceand said reference potential; a first electrical conductor connectedbetween said second terminal of said third electronic control device andone of said second plurality of terminals associated with a thirdpredetermined one of said switching elements; and an eighth impedanceelectrically connected between said third terminal of said secondelectronic control device and another terminal of said second pluralityof terminals associated with said third predetermined one of saidswitching elements.
 12. An electronic combination lock characterized inaccOrdance with claim 9, wherein said fourth means includes: a thirdelectronic control device having a first terminal, a second terminal,and a third terminal: a fourth electronic control device having a firstterminal, a second terminal, and a third terminal; said second terminalof said first electronic control device being electrically connected toone of said second plurality of terminals associated with one of saidswitching elements; an impedance electrically connected between saidthird terminal of said third electronic control device and one of saidsecond plurality of terminals associated with said one switchingelement; an impedance electrically connected between said third terminalof said third electronic control device and said reference potential; animpedance electrically connected between said second terminal of saidthird electronic control device and said reference potential; animpedance electrically connected between said second terminal of saidthird electronic control device and said third terminal of said fourthelectronic control device; an impedance electrically connected betweensaid second terminal of said fourth electronic control device and saidreference potential; an impedance electrically connected between saidthird terminal of said fourth electronic control device and saidreference potential; said third terminal of said fourth electroniccontrol device being electrically connected to one of said firstplurality of terminals associated with said first predeterminedswitching element; another one of said first plurality of terminalsassociated with said first predetermined switching element beingelectrically connected to said reference potential; said second terminalof said fourth electronic control device being electrically connected toone of said second plurality of terminals associated with a secondpredetermined switching element; an impedance electrically connectedbetween said third terminal of said second electronic control device andanother of said second plurality of terminals associated with saidsecond predetermined switching element; and wherein said first terminalof said first electronic control device, said first terminal of saidsecond electronic control device, said first terminal of said thirdelectronic control device, and said first terminal of said fourthelectronic control device are all electrically connectable to saidsource of electrical power.